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Male Reproductive System: Erection, Orgasm, and Ejaculation Erection Parasympathetic nervous system stimulates erectile tissue Become engorged with blood Orgasm Sperm cells propelled out of testes into urethra Secretions from accessory organs also released into urethra Ejaculation Semen is forced out of urethra Sympathetic nerves then stimulate erectile tissue to release blood Penis returns to flaccid state

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FEMALE REPRODUCTIVE SYSTEM

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Female reproductive System I Function is to: Produce gamates (ova) Receive the male gamates Provide a suitable environment for: fertilisation Development of fetus Provide a means of expelling the developed fetus during parturition (birth)

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Spermatogenesis 1 Each testis is packed with seminiferous tubules In these Spermatogenesis takes place Spermatogonia (germ cells) line the tubules dividing my mitosis to give more spermatogonia (Type A and Type B)

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Spermatogenesis 2 Type B Spermatogonia will undergo meiosis to eventually form spermatozoa Type B also known as primary spermatocytes After the first meiotic division they become secondary spermatocytes

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Spermatogenesis 3 Secondary spermatocytes rapidly under go the second meiotic division to form spermatids Spermatids undergo development into spermatozoa

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Spermatogenesis 4

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Spermatogenesis 5 During spermatogenesis, cells are supported by Sertoli Cells Testes also produce testosterone from Leydig cells Controls rate of sperm production and male characteristics

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Oogenesis 1 The process primordial germ cells (oogonia) become ova Begins in fetus – oogonia divide by mitosis By 4 or 5months, some are enlarged – potential to become gametes Now called primary oocyte

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Oogenesis 2 Primary oocytes begin first stage of meiosis By month 7 they are surrounded by follicular cells to form primary follicles Then Meiosis stops until puberty

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Oogenesis 3 Once a month some of the primary oocytes continue meiosis move to surface of ovary One reaches maturity, others degenerate First meiotic division finishes – secondary oocyte Ovulation  follicle ruptures, oocyte released (once released called ovum) 2 nd Meiotic division doesn’t occur until the head of a spermatozoan enters the ovum

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Pregnancy: Fertilisation Pregnancy – condition of having a developing offspring in the uterus Fertilisation – process in which a sperm cell unites with an ovum; results in pregnancy Only one sperm cell penetrates the follicular cells and the zona pellucida that surround the ovum’s cell membrane

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Acrosome reaction

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After fertilization, ovum releases enzymes that cause the zona pellucida to become impenetrable to other sperm Zygote forms from union of ovum and sperm Contains 46 chromosomes

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Fertilisation & Implantation

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Pregnancy: The Prenatal Period Time before birth Zygote – undergoes rapid mitosis First week after fertilization Cleavage – rapid cell division Morula – ball of cells resulting from cleavage Travels down fallopian tube to uterus Becomes blastocyst which implants in endometrial wall Blastocyst Some cells (inner cell mass) become embryo Others, along with cells from uterus, form placenta